This invention relates generally to a valve for irrigation pipe and more particularly to an improved sliding gate assembly for controlling the flow through an outlet opening formed in the pipe.
Although sliding gate valves of the general type shown in U.S. Pat. No. 2,918,251 have achieved considerable popularity, they have not been wholly free of difficulties. Such gates are typically assembled by connecting the interior sealing boot to the exterior slide member by a screw which extends through the pipe opening. The assembly and disassembly of the screw connected gates involves a cumbersome and time consuming procedure, and it is also necessary to loosen and retighten the screw each time the gate is to be moved.
Due to the problems associated with screw connected gates, efforts have been made to develop gate devices that are more easily assembled and disassembled, such as those disclosed in U.S. Pat. Nos. 3,327,990 and 3,539,149. However, the assembly, and particularly the disassembly, of these snap together gates has not proven to be significantly easier than in the case of the screw connected gates. Furthermore, existing gates that are constructed for snap together assembly include only a single pair of connecting elements which hold the sealing boot and slide member together, and this single connection is often inadequate to maintain the entire surface area of the boot against the pipe. The seal is most susceptible to failure near the opposite ends of the boot because of the tendency in the prior art to establish the connection in a direction transversely of the boot. Consequently, it is not common for substantial water leakage to occur, particularly under conditions of high water pressure.
It is an object of the present invention to provide an improved sliding gate valve for an irrigation pipe which may be assembled and disassembled more easily than existing gates.
An additional object of the invention is to provide a sliding gate assembly which effects a sufficiently tight seal entirely around the pipe opening to prevent any water leakage, even under high pressure operation. This result is due primarily to the unique construction of the connecting elements which establish a connection that extends longitudinally for a substantial distance on opposite sides of the center line of the boot, thereby holding both ends and both sides of the boot tightly against the interior surface of the pipe.
A further object of the invention is to provide a sliding gate in which the connecting elements are shielded against exposure and yet are readily accessible to permit disassembly.
Another object of the invention is to provide a sliding gate assembly that is installed on the irrigation pipe in a manner to permit smooth and easy movement between its open and closed positions.
A still further object of the invention is to provide a sliding gate in which rotation of the gate components relative to one another and to the pipe is prevented.
Yet another object of the invention is to provide a sliding gate assembly which can be mass produced at a low cost and which is constructed of corrosion resistent materials.